Work machines including conveying machines such as forklift and construction machines or mining machines such as excavator and dump truck are used in various kinds of construction sites. In some of such work machines, abnormality of the work machine is monitored by detecting occurrence of the abnormality on the basis of operation information of the work machine which is received from various kinds of sensors. For example, Patent Literature 1 describes a technique for storing snapshot data according to the occurred abnormality to a snapshot data storage unit, on the basis of the order of priority defined in accordance with the degree of urgency for coping with the occurred abnormality.